JPS62141111A - Dry jet-wet spinning - Google Patents

Abstract

PURPOSE:To reduce frictional resistance and obtain yarns drawable at a high ratio with little fluff, surface flaw, uneven fineness, etc., by giving ultrasonic vibration to a guide for deflecting yarn running direction in a coagulation bath in dry jet-wet spinning of a polymer. CONSTITUTION:A polymer solution is extruded, run in a gas once and then led to a coagulation bath in a dry jet-wet spinning process. In the process, ultrasonic vibration at 20-40kHz frequency is normally given to a guide for deflecting yarn running direction normally provided just under a spinneret in the coagulation bath, preferably 2.5-15mm curvature radium to afford the aimed yarns. This process is useful in the dry jet-wet spinning process for an acrylonitrile based polymer, containing >=90% acrylonitrile and used for carbonizing raw material fibers requiring particularly high-degree of uniformity.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a guide for changing the running direction of yarn in a coagulation bath of dry-wet spinning, which has low frictional resistance with the yarn, and The present invention is a method that makes it possible to obtain yarn with uniform properties.

[Prior Art] A wet spinning method is employed as a method for spinning polymers that do not melt by heating or polymers with an extremely high degree of polymerization into fibers. A variation of this wet spinning method is the so-called dry-wet spinning method. This is a method in which the polymer discharged from the spinneret travels through the gas and then is immediately introduced into the coagulating liquid to coagulate. However, unlike simple wet spinning, drafts are localized in the gas, resulting in more A feature of this method is that it enables spinning at high speed or high draft.

In the above-mentioned dry-wet spinning, the polymer is generally discharged from above, and the running direction of the yarn is changed to the take-up direction in a coagulation bath. The guide used in this case is: Since it is a guide that comes into contact with the pseudo-fixated thread, various considerations have been conventionally taken.

For example, when using a rotating guide, to avoid problems such as winding of the single yarn due to the influence of the accompanying liquid flow, it is necessary to attach a belt to the rotating guide. 54-93514).For fixed guides, consideration has been given to specifying the surface roughness within a specific range (Japanese Patent Application Laid-Open No. 55-142719). Maintaining the roughness within a certain range is extremely complicated in terms of management, considering wear caused by friction with the yarn.

In the melt spinning method, there are known examples of increasing the convergence of yarn running at high speeds of 500 m/rn or more by applying ultrasonic vibration to the guide, and attempts to improve the drawability by using it in a drawing bin. There is (Special Public Interest Publication No. 47-42041)
).

[Problems to be Solved by the Invention] The present invention uses a guide for changing the traveling direction of the yarn in the coagulation bath in the dry-wet spinning described above, which has a substantially mirror surface with a surface roughness of IS or less. The object of the present invention is to provide a structure that has low contact frictional resistance and is not easily affected by surface conditions. In wet-dry spinning, the guide inevitably comes into contact with the yarn in the coagulation bath, which may cause problems such as curling the yarn or scratching the surface. greatly controls the quality of the product, especially its strength properties. Furthermore, according to the findings of the present inventors, if excessive additional tension is applied due to friction in the coagulation bath, the subsequent drawability is affected, making it impossible to obtain high-strength yarns by drawing at a high magnification. It is accepted that

From this point of view, the present inventors aim to provide a method for producing high-strength, high-quality dry-wet-spun fibers by optimizing the guide.

Means for Solving Problem E] As a result of intensive studies to solve the above problem, the present inventors have found the following specific means.

That is, ultrasonic vibrations are applied to the guide that changes the direction of the running yarn in the coagulation bath.

Usually, the guide is provided in the coagulation bath directly below the nozzle, and changes the running direction of the yarn to the direction of take-up. In another application by the present inventors, the radius of curvature of the welded portion of the guide is 0.1 to 1.
There is a proposal that the contact resistance can be reduced by reducing the radius of curvature to about 5rnrn, but when the radius of curvature is small like this, the turning angle of the thread cannot be made very large.
An extremely thin rod-like material has the drawback of being deformed by the tension of the yarn.

In the present invention, the radius of curvature of the guide is relatively large and dimensionally stable, specifically, the radius of curvature is 2.
Applicable to 5-15 mm.

If it is thicker than 15 mm, the contact area of the yarn with the guide will become too large, and a very large rigid body will be vibrated by ultrasonic waves, which not only requires an increase in the applied energy. This also causes the entire Ct i1M to vibrate, which is undesirable.

In addition, it is possible to use a guide with a matte finish, but the feature of the present invention is the surface roughness.
The advantage is that it can be applied to a substantially mirror surface having a surface of S or less, or in some cases, 0.58 or less. In general, when using a material with a satin finish as a guide without applying ultrasonic vibration, the surface condition must be observed and checked, otherwise damage to the thread will often occur. After a certain level of satin finishing, consideration must be given to further smoothing the surface. In addition, in the present invention, since the guide is vibrated by ultrasonic waves, the contact pressure on the thread is low, and as mentioned above, even if a substantially mirror-surfaced guide is used, the frictional resistance is small, and it is possible to distinguish between matte and mirror-surfaced. There is no need to do this.

There are no particular limitations on the ultrasonic waves to be applied, but the frequency is preferably about 20 to 40 kHz. Further, the energy level depends on the scale of the device, but is suitably about several 10 watts to several 1000 watts. In particular, in order to prevent vibrations from being transmitted to and spreading to the walls of the coagulation bath, consideration must be given to fixing the guide with a vibration-proof rubber or the like so that only the guide is vibrated.

Polymers to which the present invention can be applied are not particularly limited as long as they can be wet-spun, but examples include polyacrylonitrile and copolymers thereof, polyvinyl alcohol, polyethylene, polypropylene, polyaramids, and derivatives thereof. I can do it.

In particular, as will be described later, extremely good results can be obtained when applied to the production of raw material fibers for carbonization which require a high degree of uniformity. In that sense, it is suitable to apply to dry-wet spinning of acrylic polymers. Examples of acrylic polymers include vinyl monomers that contain at least 90% acrylonitrile and can be copolymerized therewith, such as acrylic acid, methacrylic acid, itaconic acid, methyl acrylate, methyl methacrylate, Mention may be made of acrylamide and derivatives thereof, allylsulfonic acid, methallylsulfonic acid and salts thereof. There are no particular restrictions on the polymerization method, and conventionally known methods may be applied as they are.

As a solvent for obtaining a spinning stock solution of these acrylic polymers, conventionally known organic and inorganic solvents are appropriately selected and used, and after being discharged from a nozzle, the solvent is allowed to run in a gas, and then introduced into a coagulation bath. . The traveling distance in this gas is usually 3 to 15rnr.
Generally, it is about n. Although there are no restrictions on the thickness of the yarn, it is applicable to yarns of 200 to 20,000 deniers.

[Effects of the Invention] By applying the guide of the present invention, frictional resistance is reduced and yarn take-up tension is reduced. As a result, not only a raw yarn with less fuzz and surface scratches due to abrasion is obtained, but also a remarkable reduction in fineness unevenness is observed. Generally speaking, applying vibration to yarn in a coagulation bath is similar to the production of thick and thin yarn, and there was a concern that unevenness in fineness would increase, but as shown in the following example, it actually does not. On the contrary, it decreases.

Although the reason for this is not necessarily clear, the present inventors estimate it as follows. That is, application of the ultrasonic vibration guide results in a reduction in the take-up tension as described above. This means that the additional tension due to the guide is reduced. This result contributes to the uniformity of the tension between the individual filaments constituting the multifilament, and at the same time is thought to have the following effects unique to wet spinning. In the coagulation bath, the solvent in the spinning stock solution is generally extracted and replaced with a non-solvent to proceed with coagulation, but especially when spinning multi-filament yarns at high speed, there is a large amount of accompanying liquid flow, and the moisture content near the yarns increases. is not constant. When the present invention is applied, one movement of the guide promotes separation and mixing of the accompanying liquid flow, and as a result, uniformity of the moisture content of the solvent and coagulant near the yarn is achieved, and a reduction in uneven fineness is achieved. It is thought that there are.

As described above, by applying the present invention, it becomes possible to collect raw yarn by dry-wet spinning with high quality and high degree of uniformity, but the present inventors have also achieved the following excellent effects. I've confirmed it. That is, in dry-wet spinning, especially in dry-wet spinning of polyacrylonitrile, there is a correlation between the take-up tension from the coagulation bath and the maximum applied magnification in the subsequent stretching process, and the lower the tension, the higher the stretching ratio. It becomes possible.

Therefore, the present invention enables the production of high-strength, highly oriented fibers, and can be suitably used in the production of raw fibers for carbonization and the production of high-strength fibers for industrial materials.

The embodiments and effects of the present invention will be specifically explained below using Examples.

In the examples, properties 11 (strength, elastic modulus) of carbon fibers are physical properties of epoxy resin-impregnated strands measured according to JIS R-7601, and represent the average value of 10 measurements. Fifty coagulated threads were randomly sampled, and the cross-sectional photograph shows the unevenness of fineness, which does not show the largest area, but is expressed by the ratio of the cross-sectional area of the single thread to the smallest single thread.

Example 1 20% DMSO bath solution 4 of acrylic copolymer consisting of 9943% acrylonitrile and 087% itacon
A polymer having a solution viscosity of 600 voices at 5°C was once discharged into the air through a nozzle with a diameter of 0.1 mm and 1000 holes, and then introduced into a 30% DMS O aqueous solution and solidified. , after pulling it vertically by a distance of 400+nm from the cap, using a folding guard
It was turned upward at the same time and was taken out of the bath using a take-up roller.

This sharpening guide has an output of 50W and a transmission frequency of 30.
A Hz ultrasonic vibrator was installed, the spinning conditions were changed, the yarn was sampled, and then the yarn was drawn continuously until the yarn was drawn at a rate of 1 and 12.
It was stretched twice and then rolled up.

20 Stabilize the yarn in air at 230 to 260°C,
It was then carbonized in a nitrogen atmosphere in a carbonization furnace with a maximum temperature of 1400°C. The characteristics at this time are shown in Table 1. As described above, it has been revealed that according to the method of the present invention, the maximum stretching ratio increases, unevenness in fineness decreases, and strand strength increases.

Claims (2)

[Claims] (1) In a wet-dry spinning method in which a polymer solution is discharged from a spinneret, allowed to run in a gas, and then introduced into a coagulation bath and coagulated, a guide for changing the direction of the yarn running in the coagulation bath is used. A wet-dry spinning method characterized by applying ultrasonic vibrations. (2) The dry-wet spinning method according to claim 1, wherein the polymer is an acrylic polymer containing 90% or more of acrylonitrile as a monomer.